Relay Beamforming Using Interference Pricing for the Two-Hop Interference Channel

Relays in cellular systems are sensitive to interference. A good relay design will mitigate received interference and will transmit in a way that avoids excess out-of-cell interference. This paper proposes a distributed relay beamforming algorithm for the two-hop interference channel, which models a relay-based cellular system. Interference pricing is used to provide the relays with information on how the interference impacts the end-to-end achievable rates. A new method is proposed to compute the interference prices via an approximation of the end-to-end achievable rate, which accounts for the relationship of the parameters in two hops. This alleviates the rate mismatch experienced by the naive application of single- hop interference pricing algorithms. Simulations show that the proposed algorithm outperforms single-hop interference pricing, zero forcing and maximal ratio transmission beamforming.